CVE-2026-3473

🔶 medium

Summary

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620

CVSS Score

5.9

Medium

EPSS Score

0.0

Exploit Probability

Published Date

2026-05-22

First Seen: 2026-05-27

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 33.4% of all 326,604 vulnerabilities in our database.

#217,570

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 22, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

eahmed

SSVC data provided by CISA

Last Modified 2026-05-22

Source NVD 🔗

CVSS Vector 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N

CWE IDs (Weakness Types)

CWE-639

📦 Affected Products 4

Vendor	Product	Status	Affected Versions
mattermost	mattermost_server	Affected	> 10.11.0 < 10.11.15
mattermost	mattermost_server	Affected	> 11.4.0 < 11.4.5
mattermost	mattermost_server	Affected	> 11.5.0 < 11.5.4
mattermost	mattermost_server	Affected	> 11.6.0 < 11.6.1

🔗 References 1

https://mattermost.com/security-updates

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-4915	🔶 medium	6.5	0.1	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil element...	2026-05-25
CVE-2026-3636	🔶 medium	4.3	0.0	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to sanitize team memb...	2026-05-22
CVE-2026-4635	🔶 medium	6.5	0.0	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channe...	2026-05-22
CVE-2026-4646	🔶 medium	4.3	0.1	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate user-supp...	2026-05-22
CVE-2026-5308	🔶 medium	4.9	0.1	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to enforce request bo...	2026-05-22
CVE-2026-5740	⚠️ high	7.5	0.1	Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to properly validate ...	2026-05-22

These CVEs affect the same products